In the context of early-stage HER2+ breast cancer in Spain, a notable diversity in therapeutic approaches was observed. The majority of interviewed medical oncologists acknowledged HER2DX as a clinically valuable test for specific patients, in line with the 2022 SEOM-GEICAM-SOLTI clinical guidelines for early-stage breast cancer. To facilitate the full integration of HER2DX into clinical guidelines, conducting prospective studies to further validate its efficacy and utility was recommended.

P1, N=20, Recruiting, Vall d'Hebron Institute of Oncology | Trial completion date: Apr 2025 --> Apr 2027 | Trial primary completion date: Sep 2024 --> Sep 2026

In our previous study, we identified the optimal peptide P1 (NPNWGRSWYNQRFK) targeting HER2 from pertuzumab, a monoclonal antibody that blocks the HER2 signaling pathway...Z8 exhibited IC50 values of 1.04 ± 0.24 μM and 1.91 ± 0.71 μM against HER2-positive SK-BR-3 and NCI-N87 cells, respectively. Moreover, superior antitumor activity and higher biosafety of Z8 were observed compared to the positive control CPT in vivo, suggesting a novel idea for the construction of PDCs.

P3, N=517, Completed, Qilu Pharmaceutical Co., Ltd. | Not yet recruiting --> Completed | Trial completion date: Dec 2022 --> Oct 2023

In this study, we evaluated the association between TILs and pathological response (pCR) and invasive-disease free survival (IDFS) in 389 patients with stage II-III HER2 positive breast cancer who received neoadjuvant anthracycline-containing or anthracycline-free chemotherapy combined with trastuzumab and pertuzumab in the TRAIN-2 trial. We found no interactions between TILs and anthracycline treatment. Our results suggest that high TIL scores might be able to identify stage II-III HER2-positive breast cancer patients with a favorable prognosis.

P1/2, N=18, Recruiting, Jonsson Comprehensive Cancer Center | Phase classification: P1b --> P1/2 | Trial completion date: Apr 2025 --> Apr 2026 | Trial primary completion date: Apr 2024 --> Apr 2025

The observed increase suggests a potential synergistic effect between these antibodies, which could enhance their therapeutic efficacy in HER2-positive cancers. These findings underscore the importance of understanding the complex interplay between therapeutic antibodies and their target antigens, providing valuable insights for the development of more effective treatment strategies.

Serum-metabolomics could be used as a powerful tool for exploring informative biomarkers for predicting or monitoring treatment efficacy. Metabolomics integrated with transcriptomics analysis could assist in obtaining new insights into biochemical pathophysiology and might facilitate the development of new treatment targets for insensitive patients.

P2, N=257, Completed, Palleos Healthcare GmbH | Active, not recruiting --> Completed

P3, N=382, Not yet recruiting, Biocon Biologics UK Ltd | Initiation date: Mar 2024 --> Sep 2024

HER2-targeting agents, such as the tyrosine kinase inhibitor lapatinib, the antibody drug conjugate (ADC) trastuzumab-emtansine or dual HER2 inhibition (pertuzumab and trastuzumab), have been investigated in the second-line setting but led to negative study results. More recently, the ADC trastuzumab-deruxtecan was authorized after the failure of trastuzumab-based treatment. However, further improvements in HER2-directed therapy are required as resistance mechanisms and HER2 heterogeneity limit the existing treatment options. This review aims to give an overview of the current standard-of-care HER2-directed therapy in gastric cancer, as well as its challenges and future developments.

The combination of neoadjuvant trastuzumab and pertuzumab with chemotherapy showed good efficiency, and the toxic side effects were tolerable in patients with BC. In cases where pCR was not achieved after neoadjuvant therapy, downregulation of HER2 and Ki-67 expressions was observed.

P3, N=4804, Active, not recruiting, Hoffmann-La Roche | Trial completion date: Nov 2028 --> Nov 2024

In our study, a third of patients with stage II-III hormone receptor-negative and HER2-positive breast cancer had a complete pathological response after only three cycles of neoadjuvant systemic therapy. A complete response on breast MRI could help identify early complete responders in patients who had hormone receptor negative tumours. An imaging-based strategy might limit the duration of chemotherapy in these patients, reduce side-effects, and maintain quality of life if confirmed by the analysis of the 3-year event-free survival primary endpoint. Better monitoring tools are needed for patients with hormone receptor-positive and HER2-positive breast cancer.

P2; These results highlight the clinical, biological, and metabolic heterogeneity of HER2+ breast cancer, which may facilitate the selection of HER2+ EBC patients likely to benefit from [18F]FDG-PET imaging as a tool to guide therapy.

Among HER2-positive EBC patients, a PET-based, pCR-adapted strategy was associated with an excellent 3-year iDFS. This strategy identified about a third of patients who had HER2-positive EBC who could safely omit chemotherapy.

In the PHERGain trial, an increased SUVmax cutoff (≥77%) after 2 cycles of exclusive HP (with or without endocrine therapy) achieves a pCR in the range of the control arm with chemotherapy plus HP (59.5% vs. 57.7%, respectively), further identifying a subgroup of patients with HER2-addicted tumors. However, the original cutoff (≥40%) maximizes the number of patients who could avoid chemotherapy.

P2, N=74, Not yet recruiting, University of Chicago

Neoadjuvant pertuzumab and trastuzumab plus CT achieve high pCR rates in real-life patients with HER2-positive early BC, showing an acceptable safety profile. Innovative adjuvant strategies are essential in patients at high risk of distant disease recurrence.

Compared to HER2 (3+) BC, the limited effectiveness of neoadjuvant trastuzumab and pertuzumab therapy for HER2 (2+)/ISH+ BC is due to subtype heterogeneity. Reassessment of targeted therapy efficacy in patients with HER2 (2+)/ISH+ BC is essential.

This real-world US study showed that approximately two-thirds of 2L patients received subsequent therapy and disease progression was the most common reason for 2L discontinuation highlighting the need for timely 2L treatment with the most efficacious drug to allow patients to achieve longer treatment duration and delayed progression.

No abstract available

Our findings suggest that radiological CR at first disease re-evaluation is associated with more prolonged survival; this might result from stronger dependence on HER2 pathway addiction, supporting the need for further translational research.

P1/2, N=20, Recruiting, Fudan University | Trial completion date: Dec 2021 --> Dec 2024 | Trial primary completion date: Dec 2021 --> Dec 2024

P3, N=347, Active, not recruiting, Hoffmann-La Roche | Trial completion date: Sep 2025 --> Dec 2025 | Trial primary completion date: Aug 2024 --> Mar 2025

P2, N=63, Active, not recruiting, City of Hope Medical Center | Trial completion date: Dec 2023 --> Dec 2024

P2, N=120, Recruiting, Shanghai Jiao Tong University School of Medicine | Not yet recruiting --> Recruiting | Initiation date: Jul 2023 --> Nov 2023

Patients (female; n = 329; randomized 2:1) received neoadjuvant pertuzumab/placebo with trastuzumab and docetaxel, followed by adjuvant 5-fluorouracil, epirubicin, and cyclophosphamide, then pertuzumab/placebo with trastuzumab until disease recurrence or unacceptable toxicity, for up to 1 year. Limitations include the lack of ado-trastuzumab emtansine as an option for patients with residual disease and the descriptive nature of the secondary, long-term efficacy endpoints. PEONY confirms the positive benefit:risk ratio of neoadjuvant/adjuvant pertuzumab, trastuzumab, and docetaxel treatment in this patient population.

The results of this study confirm a clinically significant benefit of trastuzumab plus pertuzumab treatment in patients with HER2+mCRC.

P2, N=25, Recruiting, Mayo Clinic | Not yet recruiting --> Recruiting

All patients initiated a combination treatment of trastuzumab, pertuzumab, and chemotherapy (TPC), and 72% moved to second-line treatment during the study follow-up period (82% ado-trastuzumab emtansine). Patients with upfront brain involvement at the time of mBC diagnosis had shorter survival compared to those who started TPC without brain metastases. Nonetheless, the overall results from this study compare favorably with previous studies and contribute to understanding the value of traditional treatment options, which will serve as a baseline for future treatment strategies in the real-world setting.

In this issue of Cancer Research, Hosni and colleagues discover a paracrine mechanism mediated by adipocyte precursor cells through which urothelial carcinomas become resistant to erdafitinib, a recently approved therapy inhibiting fibroblast growth factor receptors (FGFR)...The NRG1-mediated FGFR inhibitor resistance was amenable to intervention with pertuzumab, an antibody blocking the NRG1/HER3 axis...Because fibroblasts with the ASC/FAP signature are enriched in various carcinomas, it is possible that the paracrine signaling conferred by NRG1 is a pan-cancer mechanism of FGFR inhibitor resistance and tumor aggressiveness. See related article by Hosni et al., p. 725.

These findings suggest a potential role of Trop-2 expression as a biomarker of resistance to neoadjuvant chemotherapy plus dual HER2 blockade and may become a strategic target for future combinations in HER2-positive EBC patients.

In this multicenter, phase II study, patients with confirmed HER2-positive early BC received four cycles of PLD (30-35 mg/m2) and cyclophosphamide (600 mg/m2), followed by four cycles of taxanes (docetaxel, 90-100 mg/m2 or nab-paclitaxel, 260 mg/m2), concomitant with eight cycles of trastuzumab (8 mg/kg loading dose, then 6 mg/kg) and pertuzumab (840 mg loading dose, then 420 mg) every 3 weeks. This dual HER2-blockade with sequential polychemotherapy showed promising activity with rapid tumor regression in HER2-positive BC. Importantly, this regimen showed an acceptable safety profile, especially a low risk of cardiac events, suggesting it as an attractive treatment approach with a favorable risk-benefit balance.

P2, N=45, Completed, IFCT

These data suggest that HER2DX risk-score in RD provides additional information on the likelihood of developing distant recurrences. In RD, high expression of immune and luminal genes was associated with a reduced risk, while high expression of proliferation genes was associated with a higher risk. Molecular changes after anti-HER2 therapy were mainly observed in RD of pts that did not relapse.

Chemotherapy-free neoadjuvant regimen with DTP in HER2-enriched EBC showed high pathologic response rates comparable to that with chemotherapy. This DTP regimen may provide an effective, relatively non-toxic, and biologically driven alternative to standard of care chemotherapy in this HER2-enriched subset of EBC.

Tumor-informed ctDNA monitoring provides insight into early treatment response and survival outcomes in patients with diverse HER2 amplified or mutated tumors receiving HER2 targeted therapy. On-treatment ctDNA dynamics refine and can potentially detect response/progression ahead of standard of care response assessments, suggesting early ctDNA monitoring as a valuable complementary tool for real-time treatment response monitoring.

In this report, we present two exceptional responses in hormone receptor-positive, HER2-nonamplified, HER2/HER3 co-mutated metastatic breast cancer patients who were treated with the anti-HER2-directed monoclonal antibodies, trastuzumab and pertuzumab. Both patients acheived exceptional responses to treatment, suggesting that combined trastuzumab, pertuzumab, and endocrine therapy could be a highly effective therapy for these patients and our observations could help prioritize trastuzumab deruxtecan as an early therapeutic choice for patients whose cancers have activating mutations in HER2.

HP was active in a selection of HER2-amplified tumors (non-breast/gastroesophageal) but did not meet the predefined efficacy benchmark. Additional strategies targeting HER2 and potential resistance pathways are warranted, especially in rare tumors.

P1, N=114, Active, not recruiting, Mabscale, LLC | Recruiting --> Active, not recruiting

In this study, we investigated the efficacy and safety of a neoadjuvant Chinese THP regimen (docetaxel, trastuzumab biosimilar TQB211 plus the pertuzumab biosimilar TQB2440 or pertuzumab) for ER/PR-negative and HER2-positive breast cancer in China. Domestic dual-target HP has a more satisfactory efficacy and safety in the neoadjuvant phase of treatment. https://clinicaltrials.gov/study/NCT05985187, NCT05985187.